De supercomplexen in het Crista-membraan

The electron chain complexes are crucial components to couple redox reactions with ATP synthesis.

They can be present on the inner mitochondrial membrane as discrete entities with mobile electron carriers transporting the electrons between two neighboring complexes.

Alternatively, a phospholipid called cardiolipin acts as molecular glue, organizing different combinations of individual complexes into respiratory chain supercomplexes or even megacomplexes.

In a supercomplex, the distance between neighboring complexes is reduced compared to individually arranged complexes.

This allows mobile electron carriers to diffuse quickly from one complex to another in the supercomplex assembly, improving their electron transfer and proton-pumping efficiencies.

In cells with high-energy demand, a respiratory supercomplex can thus generate a large proton-motive force for upregulating the ATP production.

In addition, supercomplexes also play a role in regulating the reactive oxygen species or ROS.

The toxic superoxide radicals are produced when reactive sites, such as iron-sulfur clusters, remain exposed to oxygen.

In a supercomplex assembly, the reactive sites become insulated by the protein environment and become inaccessible to oxygen, thereby preventing excessive ROS formation.